1. Field of the Invention
The present invention relates to a technique for transmitting, receiving, or relaying an image through an electronic mail.
2. Description of the Related Art
Internet facsimile, in which the entirety or a portion of the function of a facsimile is substituted by the Internet, is currently spreading rapidly. In this technique, a transmission process and a reception process are controlled by an electronic mail address which is set according to a regulation of RFC (Request For Comment) 3192. For example, in an off-ramp transmission, by transmitting to an electronic mail address of “FAX=012345@relay.fax.com” an electronic mail to which a scanned image is attached, a device having a domain name of “relay.fax.com” can be instructed to transmit the scanned image via facsimile to the facsimile number of “012345.” Alternatively, in a box-storage transmission, for example, by transmitting to an electronic mail address of “BOX001@fax.com” an electronic mail to which a scanned image is attached, a device having a domain name of “fax.com” can be instructed to store the scanned image in a security box which is named “BOX001.” The “security box” refers to a storage region which is personally assigned to the user.
In the Internet facsimile described above, the image can be made secret or the like on the network using an encrypted mailing protocol such as S/MIME (Secure Multipurpose Internet Mail Extensions). However, a public key certificate is normally issued for each electronic mail address. Therefore, in a system in which the electronic mail address is changed every time the transmission destination of the facsimile or the box number is changed, such as the system of the off-ramp transmission and the system of the box-storage transmission as described above, a new public key certificate must be prepared every time the electronic mail address changes. Therefore, such a configuration requires a high cost and a certain processing time and is not suited for practical use.